In terms of impact, the OPM data breach involving security clearance information is almost certainly the most severe data breach in American history. The media has focused too much on social security numbers in its reporting, but is slowly starting to understand the bigger issues for anyone who has a clearance, or is a relative or neighbor or friend of someone with a clearance.

But the news got me thinking about the issue of SSNs, and how widespread they are. The risks of SSNs as both authentication and identifier are well known, and over the past decade, many organizations have tried to reduce their use of and reliance on SSNs, to minimize the damage done if (or maybe I should say “when”) a breach occurs.

In this blog post, I’m going to describe three recent cases involving SSNs that happened to me, and draw some lessons.

Like many suburbanites, I belong to Costco (a warehouse shopping club ideal for buying industrial quantities of toilet paper and guacamole, for those not familiar with the chain). A few months ago I lost my Costco membership card, so I went to get a new one, as a card is required for shopping in the store. The clerk looked up my driver’s license number (DL#) and couldn’t find me in the system; searching by address found me – but with my SSN as my DL#. When Costco first opened in my area, SSNs were still in use as DL#s, and so even though my DL# changed 20 years ago, Costco had no reason to know that, and still had my SSN. Hence, if there were a Costco breach, it’s quite possible that in addition to my name & address, an attacker would also get my SSN, along with some unknown number of other SSNs from long-term members. Does Costco even know that they have SSNs in their systems? Perhaps not, unless their IT staff includes old-timers!

A recent doctor’s visit had a similar result. The forms I was asked to fill out asked for my insurance ID (but not my SSN), however the receipt helpfully provided at the end of my visit included my SSN, which I had provided the first time I saw that doctor 25 years ago. Does the doctor know that his systems still have SSNs for countless patients?

Last fall I did a TV interview; because of my schedule, the interview was taped in my home, and the cameraman’s equipment accidentally did some minor damage to my house (*). In order to collect payment for the damage, the TV station insisted on having my SSN for a tax form 1099 (**), which they helpfully suggested I email in. I had to make a decision – should I email it, send it via US mail, or forgo the $200 payment? (Ultimately I sent it via US mail; whether they then copied it down and emailed it, I have no idea.) I got the check – but I suspect my SSN is permanently in the TV station’s records, and most likely accessible to far too many people.

These cases got me thinking where else my SSN is floating around, perhaps in organizations that don’t even realize they have SSNs that need to be protected. The grocery store probably got my DL# decades ago when it was still my SSN so I could get a check cashing card, and that number is probably still on file somewhere even though I haven’t written a check in a grocery store for 10 or 20 years. The car dealer that sold me my car five years ago has my SSN as part of the paperwork to file for a title with the Department of Motor Vehicles, even if they don’t have it from my DL#. Did they destroy their copy once they sent the paperwork to DMV? I’m not betting on it. I cosigned an apartment lease for my daughter before she had her own credit history close to 10 years ago, and that required my SSN, which is probably still in their files. I met a sales person 20 years ago who had his SSN on his business card, to make it easier for his customers in the classified world to look him up and verify his clearance. (I probably have his business card somewhere, but luckily for him I’m not very organized so I can’t find it.) Many potential employers require an SSN as part of a job application; who knows how many of those records are floating around. Luckily, many of these files are paper records in a file cabinet, and so mass breaches are unlikely, but it’s hard to know. Did any of them scan all of their old files and post them on a file server, before destroying the paper copies?

As many people have suggested, it’s time to permanently retire SSNs as an authenticator, and make them just an identifier. Unfortunately, that’s much easier said than done. Todd Davis, CEO of Lifelock, famously put his SSN on his company’s advertising, and was then the victim of identity theft. We all know that the “last four” of your SSN has become a less intrusive (and even less secure!) substitute authenticator.

So what should we do? If you’re a CIO or in a corporate IT department, think about all the places where SSNs may be hiding. They’re not always obvious, like personnel records, but may be in legacy systems that have never been cleaned up, as is probably the case for Costco and my doctor. And once you get finished with your electronic records, think about where they’re hiding in paper records. Those are certainly lower risk for a bulk theft, but they’re at some risk of insider theft. Can the old (paper) records simply get shredded? Does it really matter if you have records of who applied for a job or a check cashing card 15 years ago?

I’m not optimistic, but I’ll keep my eyes open for other places where SSNs are still hiding, but shouldn’t be.

(*) Since you insist: one of the high intensity lights blew up, and the glass went flying, narrowly missing the producer. Two pieces melted into the carpet, ruining small sections. The staff were very apologetic, and there was no argument about their obligation to reimburse me for the damage. The bigger damage was that I spent an hour being interviewed on camera, and they used about 10 seconds in the TV piece.

(**) Yes, I know they shouldn’t need an SSN for reimbursement, but I unsuccessfully tilted at that windmill.

Hackers published online Monday thousands of personal records from 53 universities, including Harvard, Stanford, Cornell, Princeton, Johns Hopkins, the University of Zurich and other universities around the world.

I stifled the instinct to do a spit-take with my morning cup of coffee.

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